Method and apparatus for storing or retrieving items

ABSTRACT

A method and apparatus are provided for storing and retrieving items to/from a plurality of destinations areas. A storage and retrieval system stores and retrieves items as needed and transfer items from storage locations to transfer locations. A separate picking system conveys the items from the transfer locations to a picking station or an input out station so that the item can be selected.

PRIORITY CLAIM

This application is a continuation of co-pending U.S. patent applicationSer. No. 16/665,849 filed on Oct. 28, 2019 and set to issue on Mar. 16,2021 as U.S. Pat. No. 10,947,044, which is a continuation of U.S. patentapplication Ser. No. 15/784,580 filed Oct. 16, 2017 issued on Oct. 29,2019 as U.S. Pat. No. 10,457,483, which is a continuation ofInternational Patent Application No. PCT/US2016/028500, filed Apr. 16,2016, which claims priority to U.S. Patent Application No. 62/150,786,filed Apr. 21, 2015. The entire disclosure of each of the foregoingapplications is hereby incorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates to a material handling system for storingor retrieving items. More specifically, the present invention relates toa material handling system incorporating a plurality of destinationareas arranged along a track for guiding a plurality of vehicles forcarrying items to and/or from the destination areas.

BACKGROUND OF THE INVENTION

Storing and retrieving items can be laborious and time consuming,especially as the number of different items increases. For example, manycompanies have tens of thousands of different of items that need to bestored and retrieved. For instance, large manufacturing companiesrequire accurate and timely storage of various parts for the productsbeing manufactured as well as components used during the manufacturingprocess. Delays in retrieving the necessary components can delay theoverall manufacturing process.

Similarly, retail companies, such as online retail companies, requirefast and accurate picking of items sold to their customers to ensurethat orders are timely fulfilled. Such online companies often stock tensof thousands of items that need to be readily available for shipment tocustomers. Systems that rely upon human effort to store and retrieveproducts in such situations tend to require more time to pick therequired products and tend to have a higher percentage of errors (i.e.retrieval of incorrect items). Therefore, there is a growing need forautomated systems designed to automatically store and retrieve items toimprove the efficiency of order fulfillment.

SUMMARY OF THE INVENTION

In light of the foregoing, the present invention provides a method andapparatus for handling items. According to one aspect, the systemincludes a plurality of storage locations, and a plurality of deliveryvehicles for delivering items to or retrieving items from the storagelocations. A track guides the delivery vehicles to the storagelocations. The system may also include a controller that controls theoperation of the delivery vehicles based on information determined foreach item to be stored. Additionally, the track may include a pluralityof interconnected vertical and horizontal sections so that the vehiclesmay travel along a continuous path changing from a horizontal directionto a vertical direction. Further, the vehicles may be driven such thatthe orientation of an item on the vehicle stays constant as the vehicleschanges from a horizontal direction of travel to a vertical direction oftravel.

According to another aspect, the present invention provides a method forstoring and retrieving items. The method includes the steps of storing aplurality of items in a plurality of storage locations and retrievingitems from the storage locations. The retrieved items are conveyed totransfer locations. The method also includes controlling or driving aplurality of picking vehicle along a track. The track may haveinterconnected horizontal and vertical sections. The track may form aloop and the loop may be a vertically oriented loop. The step ofcontrolling the vehicles may comprise the step of circulating thepicking vehicles around a track between one or more picking stations andthe transfer locations. The step of circulating the picking vehicles mayinclude driving one of the picking vehicles to one of the transferlocations and transferring one of the retrieved items from the transferlocation onto the picking vehicle. The picking vehicle may then bedriven from the transfer locations to one of the picking stations. Atthe picking station, the picking vehicle may be stopped so that the itemcan be picked off the picking vehicle. After an item is picked, thepicking vehicle may be advanced away from the picking station to one ofthe transfer locations. Optionally, the picking vehicle is controlled sothat the horizontal orientation of the picking vehicle is maintained asthe picking vehicle drives from the first connecting leg to the lowerleg.

According to yet another aspect, the present invention provides amaterial handling system that includes a storage and retrieval systemhaving a plurality of storage locations for storing items and means forstoring and retrieving items operable to retrieve items from the storagelocations and move the items to one or more transfer locations. Thesystem further includes mean for picking operable to transfer items toand from transfer locations. Optionally, the means for picking mayinclude a plurality of picking vehicles for transporting items betweenan input/output station and one of the transfer locations. The means forpicking may also include means for controlling the vehicles so that thevehicles are driven to an area adjacent one of transfer locations totransfer items between the picking vehicle and the transfer location.The vehicles may be controlled so that the vehicles are driven to theinput/output station and maintained at the input/output station to allowremoval of one of the items on the picking vehicle. Optionally, eachvehicle may comprise a motor for driving the means for driving thevehicle.

According to a further aspect, the present invention provides a materialhandling system that includes a storage and retrieval system fortransferring items to a plurality of transfer locations and a separateinput/output system for transferring items to and from the transferlocations. Optionally, the storage and retrieval system includes aplurality of storage locations for storing items. The storage andretrieval system may also include a plurality of independently operabledisplaceable storage and retrieval vehicles operable to retrieve itemsfrom the storage locations and convey the items to one or more of thetransfer locations. Optionally, the input/output system includes aplurality of picking vehicles for transporting items. The input/outputsystem may also include a picking track for guiding the pickingvehicles. Optionally, the track comprises a loop. There may also be aninput/output station along the track where an item can be removed fromone of the delivery vehicles. Additionally, the picking vehicles mayoptionally circulate around the loop between the input/output stationand the one or more transfer locations. Additionally, optionally thepicking vehicles may be configured differently than the optionaldisplaceable storage and retrieval vehicles. The system may controloperation of the picking vehicles so that the vehicles are driven alongthe picking track adjacent one of transfer locations to transfer itemsbetween the picking vehicle and the transfer location.

According to yet another aspect, the present invention provides astorage and retrieval system that includes a storage and retrievalsystem and a picking system. The storage and retrieval system includes aplurality of storage locations for storing items and a displaceablestorage and retrieval device movable between the storage locations. Thedisplaceable storage and retrieval device is operable to retrieve itemsfrom the storage locations and move the items to one or more transferlocations. The picking system operable to transport items to and fromthe one or more transfer locations and includes a plurality of pickingvehicles for transporting items a picking track for guiding the pickingvehicles and an input/output station along the track. The input/outputstation is configured so that an item can be removed from one of thedelivery vehicles. The picking track includes a loop and is configuredso that the picking vehicles are operable to circulate around the loopbetween the input/output station and one or more of the transferlocations. The picking system is configured to control operation of thepicking vehicles so that the vehicles are driven along the track to anarea adjacent one of transfer locations to transfer items between thepicking vehicle and the storage and retrieval system at the transferlocation. The picking system is configured to control operation of thepicking vehicles so that the picking vehicles are driven from one of thetransfer locations to the input/output station to allow removal of itemsfrom the picking vehicle.

Optionally, the displaceable storage and retrieval device may beconfigured differently than the picking vehicles. For instance, thedisplaceable storage and retrieval device comprises a plurality ofstorage and retrieval vehicles, wherein the storage and retrievalvehicles are of a first type and the picking vehicles are of a secondtype that is different than the first type.

Additionally, the displaceable storage and retrieval device may comprisea plurality of storage and retrieval vehicles and the storage andretrieval system may comprise a storage and retrieval track that guidesthe storage and retrieval vehicles. The storage and retrieval track maybe separate from the picking track. For instance, the storage andretrieval track may terminate separate from the picking track to preventstorage and retrieval vehicles from entering the picking track. Inparticular, the system may include a stop that impedes displacement ofthe storage and retrieval vehicles onto the picking track. Optionally,the stop may comprise a wall of the picking track.

According to another aspect, the storage and retrieval system may beconfigured to impede displacement of the displaceable storage andretrieval device into the picking track. Additionally, each pickingvehicle may comprise a substantially horizontal support for supportingitems in a generally horizontal orientation. Optionally, the system mayinclude a transfer mechanism for transferring items from the storage andretrieval devices to the transfer locations. The transfer mechanism maybe mounted on one of the picking vehicles.

Optionally, each transfer location may comprise two sections, a firstsection configured to receive items from the displaceable storage andretrieval device and a second section configured to receive items fromthe picking vehicles. Additionally, each transfer location may comprisea conveyor for conveying items between the first section and the secondsection. Further still, the storage and retrieval system may beconfigured so that the displaceable storage and retrieval device isoperable to transfer items directly onto one of the picking vehicles.

According to a further aspect, the present invention provides a materialhandling system that includes a storage and retrieval system and aninput/output system. The storage and retrieval system may include aplurality of storage locations for storing items and a plurality ofindependently operable displaceable storage and retrieval vehiclesoperable to retrieve items from the storage locations and convey theitems to one or more transfer locations. The storage and retrievalvehicles also may be displaceable between the plurality of storagelocations. The input/output system may be operable to transfer items toand from the one or more transfer locations. Additionally, theinput/output system may include a plurality of picking vehicles fortransporting items, a picking track for guiding the picking vehicles andan input/output station along the track. The input/output station may beconfigured to facilitate removal of an item from one of the deliveryvehicles. Additionally, the track may include an loop and the pickingvehicles may circulate around the loop between the input/output stationand the one or more transfer locations. Further, the picking vehiclesmay be configured differently than the displaceable storage andretrieval vehicles.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary and the following detailed description of thepreferred embodiments of the present invention will be best understoodwhen read in conjunction with the appended drawings, in which:

FIG. 1 is a perspective view of a storing and retrieving apparatus andnumerous storage bins;

FIG. 2 is another perspective view of the apparatus shown in FIG. 1,with many of the storage bins removed;

FIG. 3 is another perspective view of the apparatus shown in FIG. 1,with many of the storage bins removed;

FIG. 4 is a side elevational view of the apparatus shown in FIG. 1;

FIG. 5 is a plan view of the apparatus shown in FIG. 1;

FIG. 6 is a fragmentary perspective view of a portion of the apparatusshow in FIG. 1, illustrating details of the transfer of bins from apicking section of the apparatus to a storage section of the apparatus;

FIG. 7 is an enlarged perspective view of a vehicle of the apparatus ofFIG. 1;

FIG. 8 is an enlarged perspective view of an alternate embodiment of avehicle of the apparatus of FIG. 1;

FIG. 9 is an enlarged fragmentary view of a portion of track of theapparatus illustrated in FIG. 1, showing details of gates in opened andclosed positions; and

FIG. 10 is an enlarged view of a wheel of the delivery vehicleillustrated in FIG. 9, shown in relation to the track of the apparatusillustrated in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the figures in general and to FIG. 1 specifically, asystem for storing or retrieving items is designated generally 10. Thesystem 10 includes a picking system 100 and a storage and retrievalsystem 400. The storage and retrieval system 400, referred to as SARsystem 400, includes numerous storage locations where items are storedfor retrieval. The SAR system 400 retrieves the items as needed andconveys the items to a destination area, such as transfer location 375.The picking system 100 includes a plurality of vehicles 200 thatretrieve items from the transfer location and convey the items to apicking station 310 where an operator can pick the item to be includedin an order for order fulfillment or otherwise. After the item ispicked, the vehicle is driven away from the picking station back to atransfer location to return items to the SAR system 400 and/or retrievefurther items. In this way, a plurality of picking vehicles circulatearound the picking system 100 transferring items to and from transferlocations while the SAR system 400 continuously transfers items betweenthe transfer locations and the storage locations.

In the following description, the picking system 100 and the SAR system400 are separate systems that interact through one or more destinationarea, such as transfer locations 375. The particular SAR system 400described below is simply one example of an SAR system that can beutilized to organize and systematically store and retrieve a largenumber of unique items that can be selected as desired.

In the embodiment illustrated in FIGS. 1-10 and described below, thesystem stores the various items in containers referred to as bins ortotes. The containers are shown as having uniform dimensions so thateach container is the same size. However, it should be understood thatthe system may be configured to use containers of varying size ifdesired. Additionally, in some applications the items may bepre-packaged so that the items are transferred directly rather thanbeing conveyed in a separate bin or tote. Accordingly, in the followingdiscussion, when a container or bin or tote is described as beingconveyed or transferred by the picking system 100 or the SAR system 400it should be understood that the item may be conveyed or transferreddirectly without using a bin or tote.

Picking System

The picking system 100 is designed so that items are retrieved from theSAR system 400 and conveyed to one or more picking stations 310 so thatitems can be picked to fulfill orders as needed. The picking system 100includes a loop of track 110 and one or more picking stations 310 andone or more transfer locations 375 are positioned along the loop oftrack. A plurality of picking vehicles 200 circulate around the loop oftrack 110 to deliver items to the picking station(s) 310 and transferitems to and from the transfer location(s) 375.

The cars 200 are semi-autonomous vehicles that each have an onboardpower source and an onboard motor to drive the cars along the track 110.The cars also include a loading/unloading mechanism 210, for loadingitems onto the cars and discharging items from the cars.

Since the system 10 includes a number of cars 200, the positioning ofthe cars is controlled to ensure that the different cars do not crashinto each other. In one embodiment, the system 10 uses a centralcontroller 350 that tracks the position of each car 200 and providescontrol signals to each car to control the progress of the cars alongthe track. The central controller 350 may also control operation of thevarious elements along the track, such as the gates 180. Alternatively,the gates may be actuated by the cars 200 as discussed further below.

Picking Track

In the present instance, the picking track 110 includes an upper rail135 and a lower rail 140. A plurality of vertical legs 130 extendbetween the upper leg and the lower leg 140. During transport, the carstravel up a pair of vertical legs 130A, 1308 from the pick station 310to the upper rail 135 (as described below, the cars actually travel uptwo pairs of rails because the track includes a forward track and aparallel opposing track). The car then travels along the upper rail andthen travel down a second column formed by vertical legs 130C, 130D. Inthe present instance, a transfer location 375 is located at the top ofthe second column. Accordingly, the picking vehicle 200 may stop at thetransfer location 375 and transfer a tote 15 to and/or from the transferlocation.

The car then travels downwardly along vertical legs 130C, 130Doptionally stopping at a transfer location positioned along the verticallegs. After transferring an item, the car travels down the vertical legsuntil reaching the lower horizontal leg 140. The car then follows thelower rail back toward the pick station 310.

As can be seen in FIGS. 1-3, the track 110 includes a front track 115and a rear track 120. The front and rear tracks 115, 120 are paralleltracks that cooperate to guide the cars around the track. As shown inFIGS. 7-8, each of the cars includes four wheels 220: two forward wheeland two rearward wheels. The forward wheels 220 ride in the front track,while the rearward wheels ride in the rear track. It should beunderstood that in the discussion of the track, the front and reartracks 115, 120 are similarly configured opposing tracks that supportthe forward and rearward wheels 220 of the picking vehicles.Accordingly, a description of a portion of either the front or reartrack also applies to the opposing front or rear track.

Referring to FIGS. 9-10, the details of the picking track 110 will bedescribed in greater detail. The track 110 includes an outer wall 152and an inner wall 154 that is spaced apart from the outer wall andparallel to the outer wall. The track also has a back wall 160 extendingbetween the inner and outer walls. As can be seen in FIGS. 9-10, theouter and inner walls 152, 154 and the back wall form a channel. Thewheels 220 of the car ride in this channel.

The track includes both a drive surface 156 and a pair of guide surfaces152, 158. The drive surface positively engages the cars to enable thecar to travel along the track. The guide surfaces 152, 158 guide thecar, maintaining the car in operative engagement with the drive surface156. In the present instance, the drive surface 156 is formed of aseries of teeth, forming a rack that engages the wheels of the cars asdescribed further below. The guide surface 158 is a generally flatsurface adjacent the rack 156. The rack 156 extends approximatelyhalfway across the track and the guide surface 158 extends across theother half of the track. As shown in FIGS. 9-10, the rack 156 is formedon the inner wall 154 of the track. The opposing outer wall 152 is agenerally flat guide surface parallel to the guide surface 158 of theinner wall.

As described above, the track includes a plurality of vertical legs130A, 130B, 130C, 130D extending between the horizontal upper and lowerrails 135, 140. An intersection 170 is formed at the intersection theupper rail 135 and vertical leg 130B, while a second intersection isformed at the intersection of upper rail 135 and vertical leg 130C.Similarly, intersections are formed at the intersection of vertical leg130B and 130C with lower leg 140.

Each intersection includes an inner branch that is curved and an outerbranch that is generally straight. The intersections at rail 130B aremirrors of the intersections with rails 130C. In FIG. 9, theintersection illustrates the portion of the track in which a verticalleg 130C intersects the upper leg 135. The intersections of the verticalleg with the lower rail incorporate similar intersections, except theintersections are reversed.

Referring to FIGS. 4 and 9, intersections 170A, 170B, 170C, 170D includepivotable gates 180. Each gate 180 has a smooth curved inner race and aflat outer race that has teeth that correspond to the teeth of the drivesurface 156 for the track. The gate 180 pivots between a first positionand a second position. In the first position, the gate 180 is closed sothat the straight outer race 184 of the gate is aligned with thestraight outer branch of the intersection (see gate 180C in FIG. 9). Inthe second position, the gate is open so that the curved inner race 182of the gate is aligned with the curved branch of the intersection (seegate 180B in FIG. 9).

Accordingly, in the closed position, the gate is pivoted downwardly sothat the outer race 184 of the gate aligns with the drive surface 156.In this position, the gate blocks the car from turning down the curvedportion, so that the car continues straight through the intersection. Incontrast, when the gate is pivoted into the open position, the gateblocks the car from going straight through the intersection. Instead,the curved inner race 182 of the gate aligns with the curved surface ofthe inner branch 172 and the car turns through the intersection. Inother words, when the gate is closed, a car goes straight through theintersection along either the upper rail 130 or the lower rail,depending on the location of the intersection. When the gate is opened,the gate directs the car from either a vertical rail to a horizontalrail or from a horizontal rail to a vertical rail, depending on thelocation of the intersection.

As can be seen in FIGS. 9-10, the end of the gate remote from the pivotpoint of the gate flares outwardly so that the curved inner race matchesthe curved profile of the inner branch when the gate is open. As aresult, the gate has a generally L-shaped configuration. To accommodatethe flared end of the gate 180, the drive surface 156 of the innerbranch has a notch or recessed portion. When the gate is closed, thenotch provides clearance so that the outer race 184 of the gate liesflat, parallel with the drive surface of the outer branch 176.

The gates 180 may be controlled by signals received from the centralcontroller 350. Specifically, each gate may be connected with anactuator that displaces the gate from the opened position to the closedposition and back. There may be any of a variety of controllableelements operable to displace the gate. For instance, the actuator maybe a solenoid having a linearly displaceable piston.

Alternatively, the gates 180 may be controlled by an actuator on thecars 200. Specifically, the gates may include a passive actuator thatresponds to an actuator on the cars. If the actuator on the car engagesthe gate actuator, then the gate moves from a first position to a secondposition. For instance, if the gate is in a first position so that thevehicle will remain along the horizontal rail and the gate actuator onthe car 200 engages the actuator on the gate, then the gate 180 willpivot upwardly into a second position so that the car will turn and movedownwardly along the vertical rail 130.

After the car 200 passes through the gate, the gate may be configured toremain in the second position until actuated by the gate actuator on thecar to return to the first position. Alternatively, after the car passesthrough the intersection, the gate 180 may automatically return to thefirst position.

In the foregoing description, the track 110 includes a single column fordriving cars upwardly and a single column which the cars followdownwardly to the lower rail 140. In such a configuration, if there is adelay in loading or unloading an item at one of the transfer locations375, the delay will impede the progress of all of the picking vehiclesin the track behind the picking vehicle that is being delayed.Accordingly, it may be desirable to extend the picking track to that thesystem includes a plurality of columns that the picking vehicles candrive down.

The additional column(s) would extend the picking track 110 into theaisle 470 in the SAR system 400. Additionally, the transfer locations375 may be elongated so that the both down columns of the picking trackare adjacent the transfer locations. In this way, the central controller350 can control the operation of gates along the picking track todetermine whether the picking vehicles travels down the first downcolumn or the second down column. Additionally, the SAR system 400controls the positioning of the tote to be retrieved by the pickingvehicle so that the tote is at the proper location along the length ofthe transfer location so that the tote can be loaded onto the pickingvehicle.

Similarly, the picking track 110 can be extended to incorporate aplurality of up columns to increase the number of picking stations 310or input stations 360 along the picking track. If two or more of upcolumns are incorporated, the system includes a number of gates and thecentral controller can control the gates to control which column towhich each picking vehicle is directed.

Picking Vehicles

Referring now to FIGS. 7-8, the details of the picking vehicles 200 willbe described in greater detail. Each delivery vehicle is asemi-autonomous car having an onboard drive system, including an onboardpower supply. Each car may include a mechanism for loading and unloadingitems for delivery. Optionally, each car may also include a gateactuator 230 for selectively actuating the gates 180 to allow thevehicle to selectively change direction.

The car 200 may incorporate any of a variety of mechanisms 210 fortransferring items between the car and the transfer areas 375.Additionally, the transfer mechanism 210 may be specifically tailoredfor a particular application. In the embodiment shown in FIG. 7, theloading/unloading mechanism 210 comprises a plurality of generallyhorizontal conveyor belt forming a platform for carrying totes or otheritems. The conveyor belts are reversible. Driving the belts in a firstdirection displaces the item toward the rearward end of the car; drivingthe belt in a second direction displaces the item toward the forward endof the car. The conveyor 210 is operable in response to signals receivedfrom the controller 350 to rotate to thereby drive items off the vehicle200 or to pull items onto the vehicle.

A conveyor motor 255 mounted on the underside of the car drives theconveyor belts 212. Specifically, the conveyor belts 212 are entrainedaround a forward roller 213 at the forward edge of the car, and arearward roller at the rearward edge of the car. The conveyor motor 255is connected with the forward roller 213 to drive the forward roller,thereby operating the conveyor belts.

Alternatively, referring to FIG. 8, the transfer mechanism 210′comprises a displaceable bar configured to engage an item stored at astorage location 190 and pull the item onto the vehicle. Morespecifically, the vehicle may include a displaceable element configuredto move toward a tote 15 in a storage location 100. After thedisplaceable element engages the tote 15, the displaceable element isdisplaced away from the storage location 100, thereby pulling the toteonto the car 200.

Referring to FIG. 8, in the present instance, the loading/unloadingmechanism 210′ may comprises a displaceable rod or bar 212. The bar 212extends across the width of the car 200 and both ends are connected withdrive chains 214 that extend along the sides of the car. A motor drivesthe chains to selectively move the chain toward or away from storagelocations. For example, as the car approaches a transfer location 375 toretrieve a tote 15, the chain may drive the rod toward the transferlocation so that the bar engages a groove or notch in the bottom of thetote. The chain then reverses so that the bar 212 moves away from thetransfer location 375. Since the bar is engaged in the notch in thetote, as the bar moves away from the transfer location 375, the barpulls the tote onto the car. In this way, the loading/unloadingmechanism 210′ is operable to retrieve items from a transfer location.Similarly, to transfer an item to a transfer location 100, the chain 214of the loading/unloading mechanism 210′ drives the bar 212 toward thetransfer location until the item is in the transfer location. The chaincontinues to advance the bar 212 so that the bar moves downwardly andthen retracts back toward the vehicle thereby disengaging the bar fromthe tote 15 to release the tote.

Additionally, since the transfer locations 375 can be located toward theforward side of the picking track 110 or the rearward side of thepicking track the system is operable to transfer items toward transferlocations 375 on the forward side of the track or the rearward side ofthe track. Specifically, as shown in FIG. 8, the loading/unloadingmechanism 210 includes two bars 212 spaced apart from one another. Onebar is operable to engage totes in transfer location adjacent the frontpicking track 115 and the second bar is operable to engage totes intransfer areas adjacent the rear picking track 120.

As previously discussed, each car may also include a gate actuator foractuating the gate from a first position to a second position so thatthe car may change directions as the car travels along the pickingtrack. The actuator may be any of a variety of elements configured toengage a corresponding element on the gate 180. The gate actuator may beselectively moveable between a first position and a second position. Inthe first position, the gate actuator is positioned so that it avoidsengagement with the gate or other engagement element(s) along the track.In the second position, the gate actuator 230 is operable to engage acorresponding element along the track to actuate the gate.

The picking vehicles 200 include four wheels 220 that are used totransport the car along the picking track 110. The wheels 220 aremounted onto two parallel spaced apart axles 215, so that two or thewheels are disposed along the forward edge of the car and two of thewheels are disposed along the rearward edge of the car.

Referring to FIG. 10, each wheel comprises an inner idler roller 224 andan outer gear 222 that cooperates with the drive surface 156 of thetrack. The idler roller 224 rotates freely relative to the axles, whilethe outer gear is fixed relative to the axle onto which it is mounted.In this way, rotating the axle operates to rotate the gear 222.Additionally, the idler roller is sized to have a diameter slightlysmaller than the distance between the upper wall 152 and the lower wall154 of the track. In this way, the idler roller may rotate freely withinthe track, while ensuring that the gear 222 of each wheel remains inoperative engagement with the drive surface (i.e. the teeth) 156 of thetrack. Accordingly, when the vehicle is moving horizontally, the rollerscarry the weight of the cart, while the gears 222 cooperate with thedrive surface 156 of the track to drive the vehicle along the pickingtrack.

The car includes an onboard motor for driving the wheels 220. Morespecifically, the drive motor is operatively connected with the axles torotate the axles 215, which in turn rotates the gears 222 of the wheels.In the present instance, the drive system is configured so that eachgear is driven in a synchronous manner. Specifically, each gear 222 isconnected to an end of one of the axles in a manner that substantiallyimpedes rotation of the gear relative to the axle. In this way, eachaxle drives the attached two gears in a synchronous manner.Additionally, in the present instance, both axles are driven in asynchronous manner so that all four gears are driven in a synchronousmanner.

There are various mechanisms that can be used to synchronously drive theaxles. For instance, a pair of drive motors can be used to drive theaxles, and the drive motors can be synchronized. Alternatively, a singledrive motor may be used to drive both axles. Each axle may include atiming pulley rigidly connected to the axle to prevent rotation of thepulley relative to the axle. Similarly, a timing pulley may be connectedto the motor shaft. The drive belt connecting the timing pulley on theaxle with the motor may be a timing belt so that rotation of the drivemotor is precisely linked to the rotation of the axle. Although a singletiming belt can be used to drive both axles synchronously, a pair oftiming pulleys may be connected to the motor shaft, and each timingpulley may be connected to a corresponding timing pulley on one of theaxles.

The drive motor may include a sensor that is operable to detect therotation of the motor to thereby determine the distance the car hastraveled. Since the gears 222 are rigidly connected with the axles,which are in turn synchronously connected with the drive motor, theforward distance that the car moves can be exactly controlled tocorrelate to the distance that the drive motor is displaced.Accordingly, the distance that a car has traveled along the determinedpath depends on the distance through which the car motor is rotated.

To detect the rotation of the drive motor the motor may include a sensorfor detecting the amount of rotation of the drive motor. For instance,the sensor 252 may be a sensor such as a hall sensor. The sensor detectsthe rotation of the motor and sends a signal to the central processor350, which determines how far along the designate path the car hastraveled based on the known information regarding the path and therotation that the sensor detects for the motor.

The car 200 may be powered by an external power supply, such as acontact along the rail that provides the electric power needed to drivethe car. However, in the present instance, the car includes an onboardpower source that provides the requisite power for both the drive motorand the motor that drives the load/unload mechanism 210. Additionally,in the present instance, the power supply is rechargeable. Although thepower supply may include a power source, such as a rechargeable battery,in the present instance, the power supply is made up of one or moreultracapacitors. The ultracapacitors can accept very high amperage torecharge the ultracapacitors. By using a high current, theultracapacitors can be recharged in a very short time, such as a fewseconds or less.

The car includes one or more contacts for recharging the power source.In the present instance, the car includes a plurality of brushes, suchas copper brushes that are spring-loaded so that the brushes are biasedoutwardly. The brushes cooperate with a charging rail to recharge thepower source, as described further below.

For instance, a pair of charging rails may be disposed beneath the lowerhorizontal rail 140. The charging rails are conductive strips connectedwith an electrical supply. The charging contacts of the car 200 engagethe conductive strips to recharge the ultracapacitors. Specifically, thebiasing element of the brushes biases the brushes outwardly toward thecharging contacts. The electricity flowing through the charging contactprovides a high amperage, low voltage source that allows theultracapacitors to recharge in a few seconds or less. In addition, sincethe power supply provided by the ultracapacitors may last for only a fewminutes, the car recharges each time it travels along the lower rail140.

Each car may include a load sensor for detecting that an item is loadedonto the car. The sensor(s) ensure that the item is properly positionedon the car. For instance, the load sensor may include a force detectordetecting a weight change or an infrared sensor detecting the presenceof an item.

In the foregoing description, the cars have drive gears that interactwith teeth in the track to guide the cars around the track.Additionally, as described further below in the operation section, thelocation of the car may be controlled based on information regarding howfar the car has traveled. In such applications, it is desirable tosynchronize the drive wheels of the car. However, in some applicationsalternative control systems may be used. For instance, the location ofthe cars can be controlled based on signals from sensors positionedalong the track or indicators positioned along the track. In suchinstances, the cars may be configured to use a drive mechanism that isnot synchronous as described above.

As discussed further below, the car further includes a processor forcontrolling the operation of the car in response to signals receivedfrom the central processor 350. Additionally, the car includes awireless transceiver so that the car can continuously communicate withthe central processor as it travels along the track. Alternatively, insome applications, it may be desirable to incorporate a plurality ofsensors or indicators positioned along the track. The car may include areader for sensing the sensor signals and/or the indicators, as well asa central processor for controlling the operation of the vehicle inresponse to the sensors or indicators.

Pick Station

As described previously, the picking system 10 is configured so that thepicking vehicles 200 retrieve items from the transfer locations 375 andtransport the items to the pick station 310. Referring now to FIGS. 1-6the pick station 310 will be described in greater detail.

In one mode of operation, the system 10 is used to retrieve items neededto fill an order. The order may be an internal order, such as partsneeded in a manufacturing process in a different department, or theorder may be a customer order that is to be filled and shipped to thecustomer. Either way, the storage and retrieval system 400 retrieves theitems from the storage areas and delivers the items to the transferlocations 375.

The picking vehicles retrieve items from the transfer locations 375 anddeliver them to the picking station 310 so that an operator can pick therequired number of an item from a tote. Additionally, in some instancesan automated mechanism can be used to automatically pick an item from apicking vehicle at the picking station. For instance, an arm or othermechanical device may reach into the tote and automatically select anitem from the tote and then remove the item or the device can remove theentire tote or container on the picking vehicle. Accordingly, it shouldbe understood that when the description or claims state that an operatorpicks an item, the operator may be a human operator or a mechanicaloperator.

After the item is picked from a tote, the car advances so that the nextitem required for the order is advanced toward the picking station 310.The system continues in this manner so that the operator can pick all ofthe items needed for an order.

In the present instance, the pick station 310 is configured so that thecar travels upwardly to present the contents to the operator so that theoperator can more easily retrieve items from the tote 15. Referring toFIG. 1, at the picking station the track includes a curved section 315that bends upwardly and away from the operator. In this way, the carmoves upwardly and then stops at a height that facilitates the operatorremoving items from the tote. After the operator removes items from thetote, the car moves away from the operator. For instance, as shown inFIG. 1, when the operator is a human operator, the track may beconfigured so that the tote moves horizontally away from the operatorand up away from the operator toward the upper horizontal rail 135.

The system can also control the operation of the cars to tilt the carsat the picking station 310 thereby making it easier for the operator toretrieve items from the tote. For instance, as the car approaches thepicking station, the controller 350 may control the car so that therearward set of wheels (i.e. the wheels in connecting leg 1106) continueto drive after the forward set of wheels stop (i.e. the wheels inconnecting leg 110A). This raises the rearward edge of the car (from theperspective of the operator). After the operator picks the items fromthe tote, the forward set of wheels (relative to the operator) drivefirst, thereby level off the car. Once leveled, the four wheels drivesynchronously. Alternatively, the picking vehicle may remain level atthe picking station and a mechanism may lift an edge of the tote to tiltthe rearward edge of the tote upward to present the contents to theoperator. Accordingly, either the picking car or the tote or both may bemanipulated to raise an edge of the tote upwardly to present thecontents to the operator at the picking station.

The pick station 310 may include a plurality of items to improve theefficiency of the pick station. For instance, the pick station mayinclude a monitor to display information to aid the operator. As the carapproaches the pick station, the system 10 may display information suchas how many items need to be picked from the tote for the order.Additionally, since the operator may pick items for multiple orders, thesystem may display which order(s) the item is to be picked for, inaddition to how many of the item are to be picked for each order. Thesystem may also display information such as how many items should beremaining in the tote after the operator picks the appropriate number ofitems from the tote.

The system may also include a sensor for sensing that an item has beenremoved from a tote so that the car can automatically advance away fromthe pick station after the operator picks the items. Similarly, thesystem may include a manually actuable item, such as a button, that theoperator actuates after picking the appropriate number of items from atote. After the operator actuates the button, the system advances thetote away from the picking station.

In the present instance, the pick station 310 is positioned at one endof the array of SAR system 400. However, it may be desirable toincorporate multiple pick stations around the SAR system. For instance,a second picking system having a second picking station can bepositioned along the opposite end of the SAR system 400. Alternatively,the SAR system 400 may have a plurality of columns and a number ofpicking systems can be positioned along an end of the SAR system.

Accordingly, it should be understood that the configuration of the trackis not limited to a single picking station. For instance, a secondpicking station may be position above the picking station 310 shown inFIG. 1. In such a configuration, the upper picking station has a trackthat intersects the upper portion of vertical tracks 130A, 1306. A gatealong the vertical tracks 130A, 1306 selectively direct the pickingvehicles toward the picking station. For instance, a gate similar to thegate 180 described above may be operable to direct picking vehiclestoward the upper picking station when the gate is in a first position,while allowing vehicles to continue up the vertical rail when the gateis in the second position. Additionally, the vertical rails 130A, 1306may include a vertical section that extends down to the lower rail 135,bypassing the first picking station. Two gates can be positioned at theintersection with the lower rail 135 so that in a first position thegates direct the picking vehicle toward the first picking station 310(shown in FIG. 1) and in a second position, the gates direct the pickingvehicle up the vertical rails 130A, 1306 bypassing the first pickingstation.

In the foregoing description, the system is discussed as being used toretrieve a discrete number of items to be used to fill an order. Theoperator picks the items from one or more totes as the totes arepresented to the operator and the operator agglomerates the items, suchas by placing the items into a container for shipping. Alternatively,rather than agglomerating a plurality of items, the system mayincorporate one or more buffer conveyors that convey items away from thesystem. The operator places the picked items onto the buffer conveyor inthe appropriate order and the conveyor(s) convey the items away from thesystem.

After the operator removes the appropriate item(s) from one of the cars,the car moves away from the pick station 310. Specifically, the onboardcontroller sends a signal to start the drive motor. The drive motorrotates the axles, which in turn rotates the gears 222 on the wheels220. The gears 222 mesh with the drive surface 156 of the vertical railsto drive the car upwardly. Specifically, the gears and the drivesurfaces mesh and operate as a rack and pinion mechanism, translatingthe rotational motion of the wheels into linear motion along the track110.

As the car moves away from the pick station, the system determines thetransfer location 375 at which the car is retrieve its next item(s) andtransfer the item(s) it is carrying. If the system is not able todetermine which transfer location the car is to be directed before thecar reaches the top of the track 110, the car can simply loop around thetrack and re-start the process.

Once the central controller 350 determines the appropriate transferlocation 375 for the item, the central controller then controls theoperation of the car to actuate the gates along the track as necessaryto direct the car to the appropriate transfer location. The car stops atthe appropriate transfer location 375 and the item on the pickingvehicle 200 is transferred off the picking vehicle. Additionally,another item may be transferred onto the picking vehicle while it isstopped at the transfer location. Alternatively, after discharging theitem at the transfer location 375, the vehicle may move to a differenttransfer location, stop and then load an item onto the picking vehicle.

Although the picking vehicle can drop-off and pick-up items at differenttransfer locations, in the present instance, the picking vehicle dropsoff an item and picks up the next item while stopped at the sametransfer station. Further still, as discussed below, in the presentinstance, while the picking vehicle is stopped to discharge a firstitem, a second item is loaded onto the picking vehicle while the firstitem is being discharged.

Referring to FIG. 9, as the wheels on the leading axle of the vehicle(i.e. the wheels traveling up rail 1306) approach the intersection 170with upper rail 135, the gate 1806 at the top of vertical rail 1306remains open and the gate 180C at the top of vertical rail 130C remainsin the closed position. Therefore, the open gate 130B allows the wheelsto drive up into the upper rail 135 and onto the outer race 184C of thegate 180C. In this way, in the closed position, gate 180C provides astraight drive surface that cooperates with the drive surface 156 toallow the lead axle of the car to travel over vertical track 130C.

Once the leading axle travels past the closed gate 180C, the gate 1806is pivoted into the closed position and the gate 180C is pivoted intothe open position. The wheels on the rear axle can then drive over theouter race of 1846 of closed gate 1806. The inner race 182C of gate 180Cthen directs the wheels on the rear axle down vertical leg 130C. At thesame time, there is no gate at the top of vertical leg 130D, so thewheels on the lead axle travel down vertical leg 130D as the wheels onthe trailing leg travel down leg 130C. As the car approaches theintersections at the bottom of legs 130C and 130D, the gates at thebottom of legs 130B and 130C are operated similarly to the abovedescription, but in reverse.

In the foregoing description, the operation of the gate 1806 isdescribed as a single gate at the top of vertical leg 1306 and a singlegate 180C at the top of vertical leg 130C. However, it should beunderstood that as described previously, the picking track 110 comprisesa front track 115 and an opposing rear track 120 that is a substantialmirror of the front track. Therefore, there are actually two of eachvertical legs 130A, 130B, 130C and 130D. Similarly, there is a gate atthe top of both vertical legs 1308 and at the top of both vertical legs130C. When the foregoing description recites that gate 1808 at the topof vertical leg 1308 is open, it actually refers to two gates beingopened: the gate at the top of vertical leg 1308 on the front track 115and the gate at the top of vertical leg 130B on the rear track 120.Similarly, when the foregoing description recites that gate 1808 at thetop of vertical leg 1308 is closed, it actually refers to two gatesbeing closed: the gate 130B at the top of vertical leg 1308 on the fronttrack 115 and the gate 1808 at the top of vertical leg 1308 on the reartrack 120. The same is true for the description of the gate 180C at thetop of vertical leg 130C.

One of the advantages of the system as described above is that theorientation of the cars does not substantially change as the cars movefrom travelling horizontally (along the upper or lower rails) tovertically (down the vertical legs 130A, 130B, 130C, 130D).Specifically, when a car is travelling horizontally, the two frontgeared wheels 220 cooperate with the upper or lower horizontal rail 135or 140 of the front track 115, and the two rear geared wheels 220cooperate with the corresponding upper or lower rail 135 or 140 of therear track 120. As the car passes through a gate and then into a column,the two front geared wheels engage a pair of vertical legs 130 in thefront track 115, and the two rear geared wheels engage the correspondingvertical legs in the rear track 120. It should be noted that when it isstated that the orientation of the cars relative to the horizon do notchange, this refers to the travel of the vehicles around the track. Eventhough the cars may tilt relative to the horizon at the picking station,the cars are still considered to remain in a generally constantorientation relative to the horizon as the cars travel along the track110.

As the car travels from the horizontal rails to the vertical columns orfrom vertical to horizontal, the tracks allow all four geared wheels tobe positioned at the same height. In this way, as the car travels alongthe track it does not skew or tilt as it changes between movinghorizontally and vertically.

Traffic Control

Since the system includes a number of cars 200, the system controls theoperation of the different cars to ensure the cars do not collide intoone another. In the following discussion, this is referred to as trafficcontrol.

A variety of methodologies can be used for traffic control. Forinstance, the traffic control can be a distributed system in which eachcar monitors its position relative to adjacent cars and the onboardcontroller controls the car accordingly. One example of such a systemutilizes proximity sensors on each car. If the proximity sensor for acar detects a car within a predefined distance ahead of the car, theonboard controller for the trailing car may control the car by slowingdown or stopping the trailing car. Similarly, if a car detects a carwithin a predefined distance behind the car, the lead car may speed upunless the lead car detects a car ahead of it within the predefineddistance. In this way, the cars may control the speed of the carsindependently based on the feedback from the proximity sensors.

Although the system may use a distributed system for traffic control, inthe present instance, the system uses a centralized system for trafficcontrol. Specifically, the central controller 350 tracks the position ofeach car 200 and provides traffic control signals to each car based onthe position of each car relative to adjacent cars and based on theroute for each car.

In the present instance, the central controller 350 operates as thetraffic controller, continuously communicating with the cars as the carstravel along the track 110. For each car, the central controllerdetermines the distance that each car can travel, and communicates thisinformation with the cars. For instance, if car B is following car Aalong the track, and car A is at point A, car B can safely travel to apoint just before point A without crashing into car A. As car A advancesto a subsequent point B along the track, car B can travel safely to apoint just before point B without crashing into car A.

The cars continuously communicate with the central controller to provideinformation indicative of their positions, so that the centralcontroller can continuously update the safe distances for each car asthe cars advance around the track.

Although the foregoing discussion is limited to determining safe zonesbased on the positions of the various cars on the track, thedetermination of safe zones is based on other factors that affect thetraffic. For instance, when calculating the safe distance for a car, thecentral controller considers the distance between the car and the nextgate, as well as the distance to the transfer location(s) to which thecar is destined.

As can be seen from the foregoing, increasing the frequency ofcommunication between the cars and the central controller increases theefficiency of the traffic flow along the track. In addition, to theforegoing variables used to calculate safe distances, informationregarding the track profile ahead of each car is used to calculate safedistances. For instance, the central controller determines whether thepath ahead of a car is sideways movement, uphill movement (i.e. movementvertically upwardly) or downhill movement (i.e. movement verticallydownwardly).

One of the issues in traffic control relates to merging at intersections170. The problem arises when a car needs to merge onto the return rail140. If two cars will arrive at the intersection close enough tocollide, one of the cars needs to have priority and the other car needsto wait or slow down to allow the first car to go through. This isparticularly true if the system incorporates a second picking stationpositioned above a first picking station as discussed above.

One method for controlling merging traffic is based on determining thenext gap large enough for a car to have time to pass through anintersection without colliding with another car. In other words, if afirst car approaches an intersection and it is determined that the gapbetween the first car and a second car is not sufficient for the firstcar to pass through, the first car waits at the intersection until thereis a gap large enough to allow the first car to pass through.

Storage and Retrieval System

As described above, the picking system 100 comprises a plurality ofpicking vehicles that circulate around a picking track 110 to drop offand receive items from one or more transfer locations positioned alongthe picking track 110. The picking vehicles then convey the retrieveditems to a picking station so that an operator can pick the requisiteitem.

The Storage and Retrieval system (SAR) 400 retrieves items from aplurality of storage locations and conveys the items to the transferlocations 375 to be picked up by the picking vehicles. Additionally, theSAR system 400 retrieves items from the picking vehicles 200 and storesthe items in the storage locations. In this way, the SAR system 400handles the storage and retrieval of items to and from thousands (orpotentially millions) of storage locations and conveys the items to oneof the transfer locations. By separating the SAR system 400 from thepicking system 100, any of a variety of SAR systems can be combined withthe picking system 100. The SAR system simply needs to be configured toconvey items from the storage locations to the transfer locations andreturn items from the transfer locations to the storage locations.

Since the picking station is operable to work in connection of any SAR400 systems, it should be understood that the configuration of the SARsystem can vary widely. Therefore, it should be understood that thefollowing description is an exemplary embodiment and is not intended tolimit the variety of SAR systems that can be used in connection with thepicking system 100.

Referring to FIGS. 1-6, the SAR system 400 will now be described ingreater detail. The illustrated SAR 400 incorporates one or more storageracks 410 having a plurality of storage locations. In the presentinstance, the storage rack comprises a vertical array of generallyhorizontal rows. A plurality of storage locations are located along eachhorizontal row and the rows are vertically spaced apart from oneanother. Additionally, in the present instance, the SAR 400 isillustrated with two parallel storage racks 410A and 410B. The storageracks 410A, 410B are spaced apart from one another creating an aisle 420between the racks.

In the foregoing description, the details of storage rack 410A will bedescribed. It should be understood that storage rack 410B is configuredsubstantially similarly to rack 410A.

The storage rack 410A comprises a plurality of horizontal supports 440connected to a plurality of vertical supports 450. Specifically, rack410 is formed of four vertical supports 450. Each row is formed by apair of parallel horizontal supports 440. Each end of each horizontalsupport is connected with one of the vertical supports. Additionally,each horizontal support 440 provides support for the row of bins ortotes 15. For instance, a shelf may be provided to support each row oftotes 15. The shelf is supported by a pair of parallel horizontalsupports 440.

As shown in FIG. 1, cross members 460 extend horizontally, transversethe horizontal supports to interconnect the vertically members to form astable rigid rack 410. As shown in FIG. 5, an aisle 470 is formedbetween racks 410A and 410B.

In the present instance, the SAR system 400 includes a plurality ofshuttles 500 for storing and retrieving items from the plurality ofstorage locations. Specifically, the shuttles 500 are positioned in theaisle 470 between rack 410A and rack 4106. The shuttles 500 drive in atrack formed on each horizontal support 440. For instance, the track maybe formed on the outside edge of each support or the track may be formedon an upper edge of each horizontal support.

In the present instance, each shuttle 500 comprises a vehicle having apair of axles and a pair of wheels are mounted on each axle. In thisway, two wheels of a shuttle are supported by a horizontal support 440of rack 410A while two wheels of the shuttle are supported by anopposing horizontal support of rack 410B as shown in FIG. 5.Additionally, as shown in FIGS. 5 and 6, the SAR system 400 isconfigured so that the SAR system operates independently of the pickingvehicles 200 and the picking track 110. In particular, the track of theSAR system 400 is separate from the picking track 110. For example, theSAR track terminates separate from the picking track 110 to impedeshuttles 500 from entering the picking track. In particular, as shown inFIG. 6, the vertical portion of the picking track 110 forms a walloperating as a stop that prevents shuttles 500 from travelling into thepicking track 110.

Although the transfer locations 375 may be located at various positionsin the SAR system 400. In the embodiment illustrated in FIGS. 1-6 atransfer location is positioned at the end of each row in each of racks410A and 410B. In this way, each row has a corresponding transferlocation at the end of rack 410A and a parallel transfer location at theend of rack 410B.

Each shuttle 500 travels back and forth along its respective row storingtotes and retrieving totes in response to commands received by thecentral controller 350. Specifically, each shuttle includes a transfermechanism for transferring totes 15 off the shuttle and into a storagelocation in the row or a transfer location at the end of the row.Similarly, the transfer mechanism is operable to load totes onto theshuttle from one of the storage locations in the row or from one of thetransfer locations at the end of the row.

The transfer mechanism for the shuttle 500 may include any of a varietyof mechanisms for transferring totes. For instance, the transfermechanism may include telescoping arms that extend from the shuttletoward the tote, engage the tote and then retracts to pull the tote ontothe shuttle. Similarly, to transfer a tote from the shuttle onto astorage location, the telescoping arms engage the tote and then extendto drive the tote toward the storage location. Once the tote is in thestorage location, the arms disengage the tote and retract back onto theshuttle. Alternatively, the shuttle 500 may include other types oftransfer mechanisms, such a reversible conveyor forming a generallyhorizontal surface on which the tote rests. By driving the conveyor in afirst direction, the tote may be ejected toward a storage location in arow of the first rack 410A, while driving the conveyor in a seconddirection ejects the tote rearwardly toward a storage location inparallel row of the second rack 410B. Similarly, a transfer mechanismmay be provided in each storage location to push or pull the totestoward or away from the shuttle. For instance, the shuttle conveyor maydrive a tote toward a storage location and then a transfer mechanism onthe storage rack can pull the tote onto the rack to pull the tote clearfrom the shuttle. Similarly, when the shuttle is a storage location, thetransfer mechanism on the rack can push a tote toward the shuttle untilthe tote engages the conveyor of the shuttle. Once the tote engages theshuttle, driving the conveyor on the shuttle pulls the tote onto theshuttle.

Accordingly, as can be seen, a variety of transfer mechanisms can beutilized to transfer the totes between the shuttles and the storagelocations. The transfer mechanisms can be mounted on the shuttles, theracks or both. In addition to transferring totes between the shuttlesand the storage locations, the transfer mechanisms are operable totransfer totes between the shuttles and the transfer locations 375.

In order to fill an order, the central controller 350 determines thelocation of each item to be retrieved and then directs the appropriateshuttles 500 to retrieve the items from the respective storage locationsand transfer the items to the transfer locations at the end of the row.The central controller then controls a corresponding number of pickingvehicles 200 to drive a picking vehicle to each of the transferlocations where an item for the order has been transferred. As a pickingvehicle 200 reaches the transfer location 375 where it is to pick up anitem, the vehicle may stop along the picking track 110 adjacent thetransfer location.

While at the transfer location 375, the system transfers an item betweenthe transfer location and the picking vehicle 200. The item may betransferred either from the picking vehicle to the transfer location orfrom the transfer location to the picking vehicle. In a typicaloperation of the system 10, while the picking vehicle is stopped at atransfer location, an item is transferred from the picking vehicle tothe transfer location and another item is transferred from a transferlocation to the picking vehicle.

More specifically, in the present instance, the items are transferred intotes 15. As a vehicle is conveyed away from the picking station 310,the central controller directs the picking vehicle to a point along thepicking track 110 adjacent two transfer locations. For instance,referring to FIGS. 1, 4-5, the picking track 100 extends into the aisle470 between SAR racks 410A and 410B so that vertical rails 130C and 130Dare positioned between transfer locations 375A and 375B. The SAR system400 controls the flow of totes so that one of the transfer locations isopen while a tote to be retrieved by the picking vehicle is on theparallel transfer location. For example, in FIG. 5, tote 15A on thepicking vehicle is to be transferred to transfer location 375A, which isopen so it can receive tote 375A. Additionally, tote 15B on transferlocation 375B is to be transferred onto the picking vehicle. As shown inFIG. 6, transfer locations 375A, 375B are located at the ends ofparallel rows in the SAR system 400 so that the two transfer locationsare at substantially the same height so that the picking vehicle cantransfer totes to and from both transfer areas while the picking vehicleis adjacent the transfer locations.

The transfer of totes between the picking vehicle and the transferlocations can be performed in series (i.e. tote 15A is transferred offthe picking vehicle and onto transfer location 375A and then tote 15B istransferred onto the empty picking vehicle from transfer location 375B.However, the operation of the system can be expedited by transferring atote onto the picking vehicle while a tote is being transferred off thepicking vehicle. To facilitate the concurrent transfer of totes, atransfer mechanism is provided at the transfer location and a separatetransfer mechanism is provided on the picking vehicle. For example, thetransfer mechanism at the transfer location may be a pusher element thatpushes tote 15B from transfer location 375B toward the picking vehicle.For instance, one or more rollers or belts at the transfer location maydrive the tote toward the picking vehicle. For example, the transfermechanism may include a plurality of roller or belts disposed betweenthe rollers at the transfer locations. To transfer the tote, the rolleror belts extend upwardly from between the rollers and engage the bottomof the tote. The rollers or belts are then driven forwardly to drive thetote toward the picking vehicle. Additionally, while the picking vehicleis stopped, the conveyor belt 210 on which tote 15A rests is actuated.By driving the conveyor belt 210 forwardly, tote 15A is driven off thevehicle and onto transfer location 375A. A transfer mechanism, such aspop-up rollers or belts described above, may engage the tote 15A todrive the tote 15A onto the transfer location. Additionally, driving theconveyor belt 210 forwardly drives tote 15B onto the picking vehiclewhile tote 15A is being discharged. In this way, a tote may be loaded onthe picking vehicle from one transfer location while a second tote isbeing discharged from the picking vehicle. In this way, the transfertime for discharging a first tote and retrieving a second tote issubstantially reduced.

As shown in FIGS. 1-6, in the present instance the transfer locationsinclude conveyors for conveying totes along the length of the transferlocations 375. For instance, the transfer locations are illustrated asbeing a series of elongated rollers for roller beds. The system includesa drive mechanism for driving the rollers to control movement of thetotes one the transfer locations.

Referring to FIG. 6, the flow of totes between the picking vehicles andthe transfer locations is illustrated. Additionally, the flow of totesalong the transfer locations is illustrated. As discussed previously,FIG. 6 illustrates a picking vehicle 200A along the picking track 110between transfer location 375A and 375B. In FIG. 6, the transfer oftotes 15A, 15B between the vehicle 220A and the transfer locations hasnot yet commenced. Below the first picking vehicle 220A, a secondpicking vehicle 220B is stopped along the picking track between transferlocations 375C and 375D. The transfer of the totes is partiallycompleted. Tote 15C is partially on the picking vehicle 220B andpartially discharged onto the transfer location 375C. Additionally, tote15D is partially loaded onto the picking vehicle 220B while a portion isstill on transfer location 375D. Below transfer location 375C is tote15E on transfer location 375E. Tote 15E has been discharged from pickingvehicle 220C which has driven away from transfer location 375E.Additionally, the rollers of transfer location 375E have been actuatedto drive tote 15E rearwardly (i.e. away from the picking system 100).Once the tote 15E is driven toward the rearward end of the roller bed,the roller bed stops so that the tote can be transferred onto one of theshuttles.

In the foregoing description, the transfer locations have been describedas staging locations where items are transferred from the shuttles sothat the items can then be transferred onto the picking vehicles.However, in certain applications, the transfer locations may bepositions along the SAR system where the shuttles are adjacent thepicking track so that items can be transferred directly from theshuttles to the picking vehicles. For instance, as shown in FIG. 5, theillustrated SAR system 400 includes shuttles 500 that operate in anaisle that is aligned with the space between the front track 115 and therear track 120 of the picking station. Instead, the SAR system 400 canbe configured so that the shuttles 500 a positioned in aisles that arealigned with where the racks are illustrated in FIG. 5. In this way,when a shuttle 500 is driven to the end of a row adjacent the pickingsystem 100, the shuttle is adjacent the picking track and positioned sothat a tote can be transferred directly from the picking vehicle to theshuttle or vice versa. Accordingly, it should be understood that theterm transfer locations includes either a staging area as shown in FIGS.1-6 or a location where a moveable storage and retrieval device, such asshuttle 500, can be positioned to transfer a tote directly with apicking vehicle stopped along the picking track.

In light of the foregoing, the following discussion describes anexemplary series of steps that the system may take to fill an order forfour separate items stored in four separate storage locations. Thesystem 10 will assign each of the four items to one of four pickingvehicles 200 as follows.

The central controller 350 calculates the theoretical time it will takethe SAR system 400 to retrieve each item in an order. Specifically, foreach of the items in an order, the central controller calculates thetheoretical time it will take a shuttle 500 to retrieve an item andtransfer the item to one of the transfer locations 375. After theestimates are determined for each item in an order, the centralcontroller 350 assigns the items to a series of picking cars to attemptto have the picking cars retrieve the items from the various transferlocations and return in the desired order or at approximately the sametime.

For instance, in an order for four items, the first item may be storedin a storage location that is farthest from one of the transferlocations and the last item may be closest to one of the transferlocations, with the second and third items in between. Accordingly, thefirst car may be assigned to retrieve the fourth item, since it will beready for pick-up first. The second and third cars may be assigned thesecond and third items in the order, and the fourth car may be assignedthe first item in the order since it will be the last item ready. Inthis way, the system controls the sequence of assigning cars to retrieveitems in order to improve the likelihood that the cars will return tothe picking station as a series of consecutive cars carrying the itemsfor the order. Additionally, it will minimize the amount of time thatpicking vehicles have to wait while the car in front of it transferitems to and/or from a transfer location. Further still, it should beappreciated, that the location of the transfer location to which apicking vehicle must go to retrieve an item may also affect the order inwhich items are assigned to the vehicles. For example, if two items inan order are stored in storage locations that are similar distances fromthe end of a row, the first picking vehicle may be assigned to retrievethe item from the transfer location that is on the lower row of thestorage rack 410. In this way, it is less likely that the second pickingvehicle will need to wait behind the first picking vehicle because thefirst vehicle is retrieving an item that is further along the track 100than the transfer location to which the second vehicle is destined.

In some applications, it is desirable to control the sequence of thecars so that the cars arrive at the picking station in the exactsequence requested for an order (i.e. First item first, second itemnext, etc). However, in many applications it is sufficient to have thecars arrive in a sequence of continuous cars having items for the order(i.e. four cars containing the items for the order without any cars inbetween the four cars with items of other orders).

Although the above description discusses assigning retrieval tasks to aseries of cars so that the cars return a sequence of cars to fill anorder, it should be understood that the picking station may beconfigured so that the operator can simultaneously pick items for morethan one order. Therefore, the system can further improve the flow ofpicking cars and the timing of the retrieval so that the picking carsreturn items for multiple orders. In essence, rather than consideringthe items for only one order and assigning the picking cars to retrievethe items for that order before assigning picking cars for the nextorder, the system can consider the items for two orders in the aggregateand assign the picking cars and shuttles 500 for all the items for aplurality of orders (such as two or three) as though the items were fora single order and assign the cars accordingly. When the picking carsreturn with the items, the system may then prompt the operator as towhich order the item is for, such as by providing an indicator on thedisplay at the pick station.

Rather than returning an item to the storage location from which it wasretrieved, the system may search for the open storage location in a rowof the next item that the car is to retrieve. The car can then unloadthe item into the transfer location for the row and the shuttle canreturn the item to an open storage location in the row. The centralcontroller then stores the location of the new storage location so thatthe items can be retrieved as necessary. In this way, the system cancontinuously re-assign the storage location of items in the SAR system400 as the items are returned to storage locations. In order to improvethe likelihood that an open storage location is proximate the next itemto be retrieved, in the present instance, the array of storage islocations is assigned so that there are more storage locations thanitems to be stored. For instance, each row in each rack 410A, 410B mayhave one or more empty storage locations. However, the number of emptystorage locations in a row may fluctuate as items are retrieved andreturned.

The SAR system 400 may be modular so that the SAR system can be expandedas necessary by attaching an additional section to the left side of rack410A or the right side of rack 4108. A second set of shuttles can thenbe operated between rack 410A or 410B and the new rack. Additionally,another picking system 100 can be provided so that the second pickingsystem transfers items between rack 410A or 410B and the new rack.

Additionally, the system can be expanded by adding additional pickingsystems 100. For instance, in the system 10 described above, a singlepick system 100 was provided at an end of the SAR system 400. A secondpicking station can be added to the opposite end of the SAR system 400so that the second picking station aligns with the aisle between theracks 410A, 410B. In this way, items can be retrieved by the shuttlesand driven to a first end of the row to transfer the item to the firstpicking system or the shuttle can be driven to the opposite end of therow so that the item can be transferred to the second picking system.Further still if a second picking station is added to that items can betransferred to a picking system at either end of each row, the number ofshuttles can be increased so that two shuttles operate along each row: afirst shuttle in a row conveys items toward the first picking system anda second shuttle in the row conveys items toward the second pickingsystem. Each shuttle in each row are independently operable, although ifa plurality of shuttles is provided in the rows, the central controllercontrols the operation of the shuttles to ensure that two shuttles donot collide.

Further, although the foregoing describes the SAR system as an array ofstorage locations in a two-dimensional array in which the SAR shuttles500 travel back and forth in a horizontal direction in X and Ydirections, as mentioned previously, the SAR system 400 may beconfigured in a number of different configurations. For example, the SARsystem 400 may include a track that extends horizontally and orvertically to allow a plurality of SAR vehicles to retrieve items from athree-dimensional array of storage locations. In such a system, thevehicles move along a track and retrieve items and then are driven toone of a plurality of transfer locations. One or more picking stationspositioned around the three-dimensional array of storage locationsretrieve the items from the transfer locations and drive the items to apicking station as described above.

It will be recognized by those skilled in the art that changes ormodifications may be made to the above-described embodiments withoutdeparting from the broad inventive concepts of the invention. Forinstance, in the above description, the system uses a wirelesscommunication between the cars and the central controller. In analternative embodiment, a communication line may be installed on thetrack and the cars may communicate with the central controller over ahard-wired communication link.

Storing Items

An input station 360 can be provided for storing new items in the systemor for re-stocking the storage locations as the item are used to fillorders. A variety of mechanisms can be used to stock items into thesystem 10. However, in the present instance, an input station 360 in theform of a conveyor or roller bed may be incorporated into the pickingsystem 100. The input system 360 is illustrated in FIGS. 1, 4 and 5.

The input station 360 is positioned along the picking track 110. Theinput station may include a mechanism for loading new items onto thepicking vehicles and a mechanism for discharging empty totes from thepicking vehicles. For instance, as shown in FIG. 5, the input stationincludes an input conveyor 360A adjacent the rear track 120 and anoutput conveyor 360B adjacent the forward track 115. Each of theconveyors 360A, 360B is operable to drive items toward or away frompicking vehicles 200 on the picking track 110. For instance, eachconveyor 360A, 360B may comprises a plurality of elongated cylindricalparallel rollers forming a roller bed. A drive mechanism, such as afriction belt selectively drives the rollers in response to signalsreceived from the central controller. In this way, when a tote 15 isempty or needs replenishment, the picking vehicle may be driven to theinput station where the tote is discharged from the picking vehicle anda new tote is transferred onto the picking vehicle.

In order to re-stock items or load new items into the system, the itemsmay be loaded into totes and then the totes are transported to the inputstation 360. For example, a series of conveyors or other transferdevices may cooperate to drive a supply of totes having items to bestored in the SAR system 400. The central controller tracks each tote asit is conveyed to the input station, so that the system knows whichitems are in which tote. In this way, when the totes are subsequentlystored in the SAR system 400, the system knows which totes are stored atwhich storage location and which items are in which totes.

The central controller controls the operation of the picking vehiclesand the input station 360 to automatically insert totes containing itemsinto the flow of totes, thereby re-stocking the system or adding newitems to the system. For instance, since the central controller 350tracks the items in each tote, the central controller knows when a toteis empty or has few enough items that the tote should be re-stocked.Similarly, if an item stored in tote becomes outdated, the system maydetermine that the tote should be discharged from the system to discardthe old items.

When the central controller determines that a tote should be dischargedfrom the system because it is empty, the items in it are outdated orotherwise, the picking vehicle carrying the tote is directed toward theinput station 360. At the input station, the tote is discharged from thepicking vehicle. For instance, the conveyor on the picking vehicle maybe activated thereby driving the tote onto the discharge conveyor. Byway of example, referring to FIG. 5, the picking vehicle 200F isconveyed to the input station. The conveyor of the picking vehicle 200Fand discharge conveyor are then actuated. The conveyor on the pickingvehicle drives the tote 15F off from the picking vehicle and thedischarge conveyor drives the tote 15F along the discharge conveyor,away from the picking vehicle. At the same time tote 15F is beingdischarged from the picking vehicle, a new tote comprising items may beloaded onto the picking vehicle 200F, similar to the manner in whichtotes are concurrently discharged and picked up at the transferlocations 375, as discussed above.

In the foregoing description, the system is re-stocked at the inputstation be loading totes containing items onto the picking vehicles,which then drive to one of the transfer locations and transfer the newtotes to the SAR system as described above. Additionally, it should beunderstood that rather than re-stocking items by inserting new totesinto the system, the totes may be re-stocked by inserting items into thetotes on the picking vehicles. For instance, an empty tote or a totehaving an empty compartment may be conveyed to the input station just asthe totes are conveyed to the picking station. At the input station,rather than picking an item from the tote, an operator (human ormechanical) places items into the tote. The picking vehicle then conveysthe tote to one of the transfer locations and the tote is stored in theSAR system 400 in the same manner as described above. The input stationmay interface with a conveyor or other mechanism from outside the track110, for loading items into the input area.

Further still, rather than re-stocking the system by loading items intototes, the items may be stored and retrieved in separate containers,such as cardboard cartons, or the items may be stored directly withoutbeing contained in a container. In such instances, rather than beinginserted into totes, the items or containers are loaded directly ontothe picking vehicles to re-stock the items.

The input station communicates with and may be controlled by the centralcontroller 350. For instance, the input station may include a scanner orother input mechanism for scanning an identification item, such as a barcode on the new items to be stored in the system. Alternatively, anoperator may identify the items at the input station and inputidentifying information into the system via an operator interface, suchas a keyboard or touch screen. In this way, the system may automaticallyidentify new stock items or an operator may input information into thesystem manually or a combination of automatic and manual data entry maybe used.

In the foregoing description, the system is described as having a singleinput station. However, it may be desirable to incorporate a pluralityof input stations positioned along the system 10. By using a pluralityof input stations, the feed rate of re-stocking items or adding newitems may be increased. In addition, the input stations may beconfigured to process different types of items. In this way, each inputstation could be configured to efficiently process a particular categoryof items.

Furthermore, rather than including separate input stations, the pickingstation(s) 310 can be used as input stations to store new items orre-stock the items. Further still, the picking system can be configuredas a re-stocking system rather than as a picking and re-stocking system.Specifically, the picking station 310 may be eliminated from the pickingtrack 110 and the system may use one or more input stations 360 tore-stock the SAR system 400 or to load new items into the SAR system.Further still, the input station 360 can operate as picking stations aswell as input stations. To fulfill an order, a tote may be dischargedfrom the picking vehicle. The tote can then be conveyed to a locationwhere an item is picked from the tote. Alternatively, in arrangements inwhich the items are transferred directly rather than being stored intotes, the items are picked by discharging the items from the deliveryvehicle.

It should therefore be understood that this invention is not limited tothe particular embodiments described herein, but is intended to includeall changes and modifications that are within the scope and spirit ofthe invention as set forth in the claims.

1-27. (canceled)
 28. A method for processing a plurality of items with amaterial handling system having a plurality of destination areas and aplurality of independently operable delivery vehicles, wherein themethod comprises the steps of: loading an item onto one of the deliveryvehicles, wherein the step of loading an item comprises the steps of:stopping the delivery vehicle at an input station; and operating atransfer mechanism to load an item onto the delivery vehicle while thedelivery vehicles is stopped at the input station; driving the deliveryvehicle vertically and horizontally along a track to one of thedestination areas after the item is loaded at the input station;transferring the item from the delivery vehicle to the destination area;accumulating a plurality of items at the destination areas by repeatingthe steps of loading, driving and transferring a plurality of times;controlling a plurality of independently operable retrieval vehicles toselectively retrieve items accumulated in the destination areas whereinthe step of selectively retrieving items accumulated in the destinationareas comprises operating a loading mechanism that is configureddifferently than the transfer mechanism; and displacing the retrievalvehicles to displace the selectively retrieved items away from thedestination areas.
 29. The method of claim 28 wherein the step ofdriving comprises maintaining the horizontal orientation of the deliveryvehicle as the delivery vehicle drives from a vertical direction to ahorizontal direction.
 30. The method of claim 29 wherein the step ofdriving comprises driving the delivery vehicle around a loop having avertical leg and a horizontal leg.
 31. The method of claim 28 whereinthe step of displacing the retrieval vehicles comprises displacing theretrieval vehicles away from the track.
 32. The method of claim 31wherein the step of displacing the retrieval vehicles comprises drivingthe retrieval vehicles along a route that is separate from the track.33. The method of claim 32 wherein the track is a first track and theroute comprises a second track that is separate from the first track.34. The method of claim 28 wherein each delivery vehicle comprises twopairs of opposing wheels and the track comprises a front track forguiding a first pair of the opposing wheels and rear track for guiding asecond pair of the opposing wheels wherein an aisle is formed betweenthe front track and the rear track, wherein the step of driving thedelivery vehicle comprises driving the delivery vehicle within the aisleto deliver the item to the one destination area.
 35. The method of claim28 wherein the step of driving the delivery vehicle comprises drivingthe delivery vehicles vertically upwardly.
 36. The method of claim 28wherein the step of operating a transfer mechanism comprises the step ofactuating a transfer mechanism that forms part of the delivery vehicle.37. The method of claim 36 wherein the transfer mechanism comprises aconveyor belt and the step of actuating a transfer mechanism comprisesdriving the conveyor belt to displace the item on the conveyor belt.